DOUBLE STARS. 203 



The importance of Christian Mayer's labors haa, long after 

 his death, been thankfully and publicly acknowledged by 

 Struve and Madler. In his two treatises, Vertheidigung 

 neuer Beobachtungen von Fizstern-trabanten (1778), and 

 Dissertatio de novis in Calo sidereo Phcenomenis (1779), 

 eighty double stars are described as observed by him, of 

 which sixty-seven are less than 32" distant from each other. 

 Most of these were first discovered by Christian Mayer him- 

 self, by means of the excellent eight-feet telescope of the Man 

 heim Mural Quadrant ; " many even now constitute very 

 difficult objects of observation, which none but very power- 

 ful instruments are capable of representing, such as p and 

 71 Herculis, e 5 Lyree, and d> Piscium." Mayer, it is true 

 (as was the practice long after his time), only measured dis- 

 tances in right ascension and declination by meridian instru- 

 ments, and pointed out, from his own observations, as well as 

 from those of earlier astronomers, changes of position ; but 

 from the numerical value of these, he omitted to deduct what 

 (in particular cases) was due to the proper motion of the stars.* 

 These feeble but praiseworthy beginnings were followed 

 by Sir William Herschel's colossal work on the multiple stars, 

 which comprises a period of more than twenty-five years ; 

 for although Herschel's first catalogue of double stars was 

 published four years after Christian Mayer's treatise on the 

 same subject, yet the observations of the former go back as 

 far as 1779 indeed, even to 1776, if we take into consider- 

 ation the investigations on the trapezium in the great nebula 

 of Orion. Almost all we at present know of the manifold 

 formation of the double stars has its origin in Sir William 

 Herschel's work. In the catalogues of 1782, 1783, and 

 1804, he has not only set down and determined the position 

 and distance of 846 double stars,t for the most part first dis- 

 covered by himself, but, what is far more important than any 

 augmentation of number, he applied his sagacity and power 

 of observation to all those points which have any bearing on 

 their orbits, their conjectured periodic times, their brightness, 

 contrasts of colors, and classification according to the amount 



* Struve, in the Recueil des Actes de la Stance publique de V Acad. 

 Imp. des Sciences de St. Pitersbourg, le 29 Die, 1832, p. 48-50. Mad- 

 ler, Astr., s. 478. 



t Philos. Transact, for the Year 1782, p. 40-126; for 1783, p. 112- 

 124 ; for 1804, p. 87. Regarding the observations oil which Sir Will- 

 iam Herschel founded his views respecting the 846 double stars, see 

 Miidler, in Schumacher's Jahrbuch fur 1839, s. 59, and his Unterwchvn- 

 gen iiber die Fixstern-Systeme. th. i.. 1847, p. 7- 



